This research project examines births to teenaged mothers from two ethnic populations over a period of half a century to better understand the etiology of low birth weight and infant death in a high risk population. The research specifically addresses current gaps in our knowledge by focusing on Mexican origin teen mothers, by providing consistently coded and high quality data on underlying and associated cause of death, and by allowing us to observe patterns in maternal and infant characteristics from 1935 to 1985. Using linked birth and death records from the tenth largest metropolitan area in the U.S., this study uses multinomial logistic regression and hazards modelling to increase our understanding of infant mortality and the health risks faced by the infants of teen mothers. Analysis of the unique cause of death data will substantially illuminate the special risks faced by teen mothers and examination of Spanish surnamed and non-Hispanic white ("Anglo") mothers will further expand the available information on ethnic differentials in high risk populations. The results will be useful not only for clarifying the academic debate regarding the role of social disadvantage for adverse birth outcomes to teen mothers, but will also provide medical and public health planners with more precise and comprehensive information regarding the risks faced by infants born to women in the teenage years.